The answer to the question posed in the title depends on what you are trying to say. Most of the time a fly is exasperating. Exasperating means annoying, as anyone who has tried to shoe away a relentless fly well knows.
Exacerbating, on the other hand, means to make worse or intensify.
As Maria pored over the 80-line GRE passage on quantum physics, a fly buzzed in her ear, exacerbating the situation.
We exacerbate a situation or condition. We can also exacerbate pain. We don’t, however, exacerbate a person, much like we can exasperate a person.
His little brother always exasperated her while she tried to do her work.
Her brother exacerbated her so she couldn’t study.
Ans: (D). Ameliorate means to improve a condition.